Boom mechanism for digging machines



CLJ

A. w. ACKER 2,784,855

March 12, 1957 BOOM MECHANISM FOR DIGGING MACHINES Filed Sept. l5, 1954United States BOOM MECHANISM FOR DIGGING MACHINES Alvin W. Acker,Topeka, Kans., assignor to Henry 'Manufacturing Company, Inc., Topeka,Kans., a cor- :poration of Kansas Application September 15, 1954, Seria]No. 456,161

3 Claims. (Cl. 214-438) -vision -o'f a boom mechanism of the classdescribed wherein the length of the boom is automatically increased asit is lowered to its digging position, and decreased as it is raised toits dumping position. This provides for the digging of holes, ditches orthe like -t-o a greater depth below the level on which the diggingmachine is positioned, without at the same time increasing the height ofthe machine when the 'boom is raised to its dumping position.

'Many similar machines are dangerously top-heavy when the `boom israised, exerting great stresses on the boom mountings, and being apt totip over, especially when being transported `over roads at substantialspeeds. The arrangement also requires less pow-er to operate the boom,since the boom length, and consequently the moment arm of the loadcarried thereby, is steadily decreased as the load is raised. Thearrangement also permits the digging of vertical-walled holes closer tothe digging machine and hence within full View of the operator, sincethe boom is relatively short when the digging depth is shallow, andprogressively lengthens as the depth increases.

Another `object is the provision of a boom mech- -anism of the characterdescribed wherein both the raising and lowering of the boom, as well asthe lengthening and shortening thereof, is accomplished by a singlepower unit.

Other objects are extreme simplicity and economy of construction,efficiency and dependability of operation, and adaptability for use withmany pre-existing types of digging machines.

With these objects in View, as well as other `objects which will appearin the course of the specification, reference will be had to thedrawing, wherein:

Fig. 1 is a side elevational View of Va 'boom mechanism for diggingmachines embodying the present invention,v

showing lthe `boom and related parts in a raised position in solid linesand in a lowered position in dotted lines, and showing the4 diggingbucket in various positions in dotted lines.

Fig. 2 is lan enlarged sectional view taken on line I-Il of Fig. l.

Like reference numerals apply to similar parts throughout the severalviews, `and the numeral 2 applies to a frame `of any suitableconstruction which is customarily mounted on a tractor or othersupporting vehicle. Said frame may also :be raised a'bove the ground fortransportation, -or lowered against the ground, which is indicated at 4,-for added stabilization and support. Said mounting and elevating means,however, form no part of Jthe present invention and `are not here shown.A boomatent 2,784,855 Patented Mar. l2, 1957 supporting standard 6 iscarried in a vertical position by frame 2. Said standard is axiallyoscillat-able on bearing members 8 carried by frame `2, Kand suitablemeans may be carried by the frame foroscill'ating said standard.However, this feature forms `no part of the present invention and saidoscillating means is not shown.

The boom 10 comprises an inner end section `12, and an outer end section14 telescoped slidably over section 12. Said boom sections arenon-circular in cross-sectional shape (square as shown) in order toprevent relativerotation thereof. The inner end Iof sectionlZ ispivotally Iattached lat 16 to a bracket 18 welded or otherwise fixed tostandard 6. A hydraulic boom cylinder 20 disposed beneath and parallelto the beam is pivoted `at 22 to a bracket 24 fixed to boom section 12.Said hydraulic cylinder is provided with a piston 26 movable therein,and a piston rod 23 fixed to `said piston and extending forwardly fromsaid cylinder, the outer end of said piston rod being pivoted at 30 to`a bracket 32 weld-ed or otherwise fixed to bo'om`sec'tion 14. Cylinder2t) is double-acting, the piston 26 therein being movable in eitherdirection by `the delivery of pressure fluid selectively to thehydraulic connections 3dand 36 at either end thereof. A rigid link 38,I-shaped in cross-sectional contour, is pivoted at one end to bracket 32at 40, and at its `opposite vend to bracket 4Z at 44, bracket 42 `beingwelded or otherwise fixedvto standard 6 in spaced apart relation belowbracket 1S.

A bucket arm 46 is provided intermediate its ends with a bracket 46fixed thereto, said bracket 'being pivoted `at Si) to the outer end ofboom section `M. A bracket 52 is fixed to the upwardly extended end ofsaid bucket arm, and is pivoted at 54s to a piston rod 56 which isattached to a piston 58, movable in a double-acting hydraulic cylinder66 having hydraulictconnections 62 and `64 xat the ends thereof. Sai-dcylinder is pivoted at 66 `to a 'bracket 63 fixed to boom `section 14 atthe inner end thereof.

A :bucket or shovel 76 which opens toward boom `10 is pivoted adjacentits: open side, at '72, to the downwardly extended end of bucket arm 46.A toggle link 74 is pivoted at one end to bucket 70 at the back orclosed side thereof, as 'at '76, and at its `opposite end is piV-oted at78 to one end of link 3%, the `opposite end of link 80 being pivoted at32 to bucket arm 46 in spaced apart relation above bucket pivot 72. Apiston rod 84 is pivotally connected `at 78, and is fixed to a piston.86 movable in a double-acting hydraulic cylinder 88 provided withhydraulic connections 90 and 92, said cylinder being pivoted at 94 tobracket 52 at the upper end of the bucket arm. The axes of all of thepivots 16, 22, 36, 40, 44, 5t), 54, 66, '72, 76, 78, 82 and 94 areparallel yand generally horizontal. The hydraulic system for energizingeach of the cylinders 2t), 66, and 88 is conventional, and is not hereshown. ln general, the system comprises suitable pumping and valvingmeans mounted on frame 2 and driven by the engine of the tractor or`other vehicle 4supporting said frame, through suitable drivingconnections.

ln operation, hydraulic cylinder S8 serves to pivot the bucket 70 withrespect to bucket arm 46, acting through toggle-linkage 741-80. Saidtoggle linkage serves to provide a greater pivotal arc for the bucketwith less movement of the hydraulic piston, thus permitting the use ofIa shorter cylinder and promoting economy. Cylinder 60 serves to pivotbucket arm @i6 relative t-o the boom. To lower the boom, iluid is fed tocylinder 20 through fluid connection 36, thereby extending piston rod 28and lengthening `the boom. Simultaneously, `the piston rod action,acting through link 38, will lower ythe boom pivotally. ln essence, theboom, standard 6?, yand link 38 form a triangular structure, the leg ofsaid triangle formed by standard 6 be fixed and the leg formed by the'boom being of adjustable length. Thus when the length of the boom isincreased `or decreased by cylinder 20, the angularity of the boom Iandlink relative to the fixed leg must change. Y

Conversely, when fluid is delivered to cylinder through connection 34,the boom is simultaneously raised and shortened. It is `of courseobvious that the actual digging movement `of bucket may be the componentresult of simultaneous operation of all three cylinders.

Certain advantages of this boom mechanism are believed clear. Forexample, when starting the digging of v a hole at `ground level, theboom is relatively short, and the bucket is therefore relatively closeto standard 6 and hence to the machine operator. As the depth of thehole increases, the length Iof the boom is correspondingly increased.Thus a vertical-walled hole may 'be dug closer t-o the stand-ard, andhence in better po-sition to be viewed by the operator, than would bethe case if the boom were of 'a xed length corresponding to the depthot' the hole to be dug. Also, as the boom is raised and shortened, themoment arm of `the load carried thereby is decreased, thereby decreasingthe power necessary to raise the boom and promoting ease of handling.When the boom is fully raised to its dumping or transporting position,its upward extension is at ya minimum. This decreases or eliminates thetopheavy nature of many machines of this type.

From an examination of the dotted line position of the boom in Fig. 1,it will be apparent that as the boom reaches its lowermost position, itapproaches parallelism with link 38. If it were Iallowed to reach actualparallelism, then -cylinder 20 could not raise the boom, since thelifting force would then 'be axial in link 3S, or dead center. Toprevent this, and preserve an `operating angularity between the boom andlink 38, piston rod 28 is so proportioned in length that piston Z6 willreach the limit of its travel at the `forward end of cylinder 20, thusarresting the downward movement of the boom, while link 38 is stilldisposed Iangularly to the boom. if desired, `other stop means could beemployed. Also, it is apparent that the degree of extension 1orretraction `of the boom vfor `any given angular movement `thereofdepends on the vertical spacing Ibetween pivots 16 and 44, `and couldthus lbe altered by setting the bracket 42, which carries pivot 44, atdifferent distances `below bracket 18, or `the setting thereof could beadjustable. These as well as other minor changes or" structure landoperation could be made without departing from the spirit of theinvention as defined by the scope of the appended claims.

What is claimed as rnew and idesired to be protected by Letters Patentis:

l. In a digging machine, a boom supporting member, a boom comprising aplurality of sections longitudinally movable relative to each other, oneend section of said boom being pivoted to said supporting member,digging members carried operatively by the other end section of saidboom, a rigid member pivoted at one end to said other Vboom section andat its opposite end to said supporting member in spaced apart rel-ationlbelow said boom pivot, and power means interconnecting the end sectionsof said boom and operable to extend or retract said boom, whereby saidboom is selectively raised `or lowered.

2. In a digging machine, a boom supporting standard, a 'boom comprisinginner and outer end sections slidably telescoped for relativelongitudinal movement, said inner end section being pivoted to saidstandard, digging members carried -operatively by said out end section,a hy draulic ram attached at its end respectively to said inner andouter boom sections whereby said boom may be extended or `retract-ed,and a rigid link pivoted at one end to said outer boom section and atits opposite end to said standard at a point spaced below the pivotalconnection of said boom to said stand-ard, `whereby said `boom islowered `as it is extended and raised as it is retracted by saidhydraulic ram.

3. The structure as s-et forth in Vclaim 2 wherein said digging memberscomprise =a bucket arm pivoted to said outer boom section, power meansoperative t-o pivot said bucket arm, la bucket pivoted to said bucket`arm 'and opening toward said boom, and power means operable to pivotsaid bucket on said arm.

References Cited in the tile of this patent UNITED STATES PATENTS2,456,491 Collins Dec. 14, 1948 2,678,741 Pilch M May 18, 1954

